Hi,

I'm hoping someone can help me here, I have a Pioneer VSX-823 A/V Receiver.

One channel has been blown.

I have followed THIS Youtube video of the same model and I have isolated the issues I believe.

In my testing I have confirmed:

1. 1 Transistor is blown failing a continuity test. The writing on the transistor is "D1560" and the PCB says "2SD1560"
2. 2 Resistors are blown for that channel

I am trying to track down these parts at my local Sayal store but I can't seem to find them. I am hoping someone can help me on the right track.

Does anyone know what the transistor D1560 specs are?

2nd: I can't seem to find the resistors. I have attached a picture. To my eyes I see. Yellow/Violet/Grey/Gold (in that order) - am I right here?

According to calculators online this is a 4.7G Ohms 5% (most likely 1 watt (maybe 1/2 watt?))

Could it be Yellow/Violet/Silver/Gold - 0.47 Ohms 5% ?

What would make the most sense here?

Sayal only carries 4.7K 47R etc. Am I doing something wrong here?

Any insight would be very helpful.

Thankyou

 

The 2SD1560 seems to be a rare bird. I did find this: https://www.el-component.com/bipolar-transistors/2sb1560 . With an Hfe of 5000 to 30000, it must be a Darlington. Those resistors are 1%'ers, so there are 3 significant digits plus the multiplier - I see 4.68K which is a standard value. Why do you think the resistors are bad?

 

When I put my multimeter on either side of the resistor there is no resistance. All the other resistors for the other 4 channels have resistance.

The 2 resistors that have no resistance are on the same circuit as the blown transistor, which also has 0 resistance.

This was the channel that was blown.

I'm not an expert on circuits but I can use a MM, and I understand the basics and can solder. Just need to know what to replace with.

For a home receiver in regards to the resistors - what do you think the color code is based on the picture I attached:

Yellow/Violet/Grey/Gold - 4.7G Ohms 5% or Yellow/Violet/Silver/Gold - 0.47 Ohms 5% ?

What would make the most sense here in this application? I believe I can get the 47R 5% 1 Watt locally.

They do have transistors but not by part name, its by specs and I'm not sure what I'm looking for.

 

When I put my multimeter on either side of the resistor there is no resistance. All the other resistors for the other 4 channels have resistance.

The 2 resistors that have no resistance are on the same circuit as the blown transistor, which also has 0 resistance.

This was the channel that was blown.

I'm not an expert on circuits but I can use a MM, and I understand the basics and can solder. Just need to know what to replace with.

For a home receiver in regards to the resistors - what do you think the color code is based on the picture I attached:

Yellow/Violet/Grey/Gold - 4.7G Ohms 5% or Yellow/Violet/Silver/Gold - 0.47 Ohms 5% ?

What would make the most sense here in this application? I believe I can get the 47R 5% 1 Watt locally.

They do have transistors but not by part name, its by specs and I'm not sure what I'm looking for.

Before you replace any resistors, unsolder one end of each of them from the board and measure them. The blown transistor may be shorting out resistors causing a bad measurement. .Measure the corresponding resistor in the good channel to find out what the value really should be. You will have to unsolder one end of them from the board too to get an accurate reading.

 

Hi,

The reason why I believe the resistors are bad as well is that when a I blew the receiver I smelled burning (which is what’s i believe was the transistor cooking up) however the unit was still working but the 1 channel sounded like a blown speaker.

In my original post where I linked the YouTube video the guy had the same exact issue.

After he replaced the transistor the audio quality was very poor on that channel and he was able to drill it down to those 2 resistors for that channel.

I only need to unsolder from one side of the resistor, correct?

 

Also correction. I made an error in my original post which I have corrected Transistor is NOT 2SD1560 it is 2SB1560

 

OK, digging a bit deeper. The resistors pictured, R28C and R29C are the emitter resistors for Q7C, a 2SB1560 (likely the one you have identified). They are indeed 0.47 ohm/2W (0R47) Manual, page 115. If Q7C developed a C-E short, it is quite possible it took out R28C and R29C. There may also be other items in the amp channel that have also failed, and you want to identify all bad parts before you install new transistors.

"Transistor is blown failing a continuity test." What exactly do you measure? You should be using your meter on the 'Diode' range and should get specific numbers for the B-E junction, the B-C junction, and C-E. You want to measure each of these in both directions, so a total of 6 measurements. Not doubting that you have correctly identified a blown transistor, but the way you worded it leaves out what might be important information.

 

Also correction. I made an error in my original post which I have corrected Transistor is NOT 2SD1560 it is 2SB1560

That one comes right up:
https://www.semicon.sanken-ele.co.jp/sk_content/2sb1560_ds_en.pdf

And the resistors in the picture are for the "Center" channel - does that correlate with the channel that appeared to fail for you?

 

I only need to unsolder from one side of the resistor, correct?

If you have the associated transistor removed, you do not need to unsolder the resistors. But do recognize that these two in parallel will be only about 0.23 ohms, and you will need to subtract out the meter lead resistance.

 

I put the MM on diode and had readings of 00 on CE, when I changed to audible mode it signalled.

BE 0.580
BC 0.580
CE 0000

On a good transistor I’m seeing 0.606 on CE

I attached a picture of the MM, to confirm I’m on the right setting.

I apologize I’m unclear what you mean 6 readings if I reverse polarity I get OL

 

Also the resistors in the picture are the Center channel because I had my wife just go take a picture just so I could see the resistors (it was hard enough to get a picture of the resistors alone let alone the correct faulty channel, lol)

The actual faulty channel is the SR however each channel component all look identical setup across the board.

The faulty transistor is indeed the SR channel along with resistors.

 

"On a good transistor I’m seeing 0.606 on CE" is a bit concerning.

C-E should normally be open in both direction, but Darlingtons, particularly when they have internal bias resistors, can be a bit misleading. Connect the base to the emitter then measure C-B/E.

 

In post #3 you use the term "no resistance". Beginners often say that when the the meter indicates over range. (Which means that the resistance is HIGHER than the meter is capable of reading.) I see from the picture of your meter that with the probes not shorted together that it displays .OL which indicates a very high resistance. If the meter really does display 0000 ohms then the transistor is faulty. I have just noticed that you have done the test in post #10 with the meter set to the diode test mode. In this mode the meter displays the voltage developed between the test leads with the test current. The 0000 reading indicates that the transistor is faulty. A good transistor should display .OL between collector and emitter (With both polarities.) The ones you say are good reading 0.606 volts I suspect you are measuring in circuit. If they give that reading out of circuit then they are also faulty.
Edit. I have just noticed that Ylli makes a good point about the possibility that the transistors are darlingtons which could explain the 0.606 volt reading.

Les.

 

I have gone through and tested all The transistors both 2SD2390 and 2SB1560

When I put the leads on one way I get OL the other way I see numerical readings.

2SD2390:

BC 0.597-0.600
CE 0.663-0.691
BE 0.623-0.628

2SB1560:
BC 0.578 - 0.582
CE 0.484 - 0.486
BE 0.602 - 0.604

Bad 2SB1560:

BC 0.579
CE 0000
BE 0.579

 

So I guess this transistor is the issue, any ideas where I can get a 2SB1560? I’m in Canada I found one but it’s $20 in shipping...

 

KP has a complementary pair, both the 2SB160 and the 2SD2390. https://kpcomponents.co/products/2sb1560-2sd2390-transistors-power-amplifier

Digikey.ca list them at $4.51. https://www.digikey.ca/product-detail/en/sanken/2SB1560/2SB1560-ND/3661806

B&D Ent (US) has them listed at $2.95. https://www.bdent.com/2sb1560-sanken-darlington-transistor.html

Don't know about shipping.

 

KP seems to have reasonable shipping rates. I will order from there.

Is this the resistor I should get?

https://kpcomponents.co/collections...r/products/0-47-ohm-1w-resistor-metal-oxide-5

I am not 100% sure if they are 1/2watt or 1 watt resistors...

Can you confirm?

Much appreciated

 

"On a good transistor I’m seeing 0.606 on CE" is a bit concerning.

C-E should normally be open in both direction, but Darlingtons, particularly when they have internal bias resistors, can be a bit misleading. Connect the base to the emitter then measure C-B/E.

That transistor has a protection diode internally connected between C and E. That is why the measured results look like that.

 

The manual parts list is not much help, as it only lists an obscure manufacturer p/n for those resistors (N113136647820-IL). Googling that number, I ran across this: "0.47W-1BK-ND RES 0.47 OHM 1W 5% AXIAL"
The schematic shows them as 0R47(2), so I would have though 2W, but it does look a bit small for 2W and I don't see any notes on the schematic as to what the (2) actually means.

Go with the 1W resistors, and if it turns out they run especially hot, you can always dig up some 2W'ers.

Oh, and since you are getting a complementary pair from KP, you may as well replace both the NPN and the PNP.

 

[QUOTE="KeithWalker]That transistor has a protection diode internally connected between C and E. That is why the measured results look like that.[/QUOTE]
Good info Keith. Doesn't show up on the receiver schematic or the data sheet I had found. But it would explain the reading.